1. Field of the Invention
This invention relates to a tilt type steering apparatus, and particularly to improvements in a portion for supporting a steering column, constituting a steering apparatus for an automobile, rockably relative to a vehicle body.
2. Related Background Art
There is known a height adjusting apparatus for a steering wheel which is called a tilt type steering apparatus designed to vary the height of the steering wheel in conformity with the constitution or the driving posture of a driver. As such a tilt type steering apparatus, there is known one described, for example, in Japanese Utility Model Publication No. 2-34145.
The tilt type steering apparatus described in this publication is called the oscillating type and is constructed as shown in FIGS. 12 to 15 of the accompanying drawings. A steering column 2, formed into the shape of a cylinder to permit a steering shaft 1 to be inserted thereinto, is divided into a front steering column 3 and a rear steering column 4. These two steering columns 3 and 4 are connected together by a support bracket 5 fixedly supported on a vehicle body. The rear steering column 4 is rockable about lateral shafts 6, 6 provided in the support bracket 5. A restraining mechanism, engageable by a tilt lever 7 rockable about the lateral shafts 6, 6, is provided between the support bracket 5 and the rear steering column 4.
More particularly, one end of the rear steering column 4 is pivotally supported on the support bracket by the lateral shafts 6, 6 provided in the support bracket 5 fixed to the vehicle body on the lower surface or the like of a dashboard 8. Also, a first engagement member 9 is fixed to the lower side of the rear steering column 4. The lower surface of this first engagement member 9 forms an arcuate convex surface centered around the lateral shafts 6, 6, and first engagement teeth 10 are formed on this lower surface.
One end (the left end as viewed in FIGS. 13 and 15) of a second engagement member 12, engageable with the first engagement member 9 with the rocking movement of the tilt lever 7, is pivotally supported on another lateral shaft 11 provided in the support bracket 5. Second engagement teeth 13, engageable with the first engagement teeth 10 formed on the lower surface of the first engagement member 9, are formed on the upper edge of the other end portion (the upper edge of the right end portion as viewed in FIG. 13) of the second engagement member 12. Also, the intermediate portion of the tilt lever 7 is pivotally supported on the lateral shafts 6, 6. A roller 15 is supported on a shaft 14 having its end portion coupled to the lower end portion of the tilt lever 7, and the upper surface of this roller 15 bears against the lower surface of the second engagement member 12. Further, a pin 18 protruding from a side of the second engagement member 12 is engaged with an inclined slot 17 formed in a rockable plate 16 fixed to the tilt lever 7.
With the construction as described above, when the tilt lever 7 is rocked counter-clockwisely, the roller 15 retracts from below the other end portion (the right end portion as viewed in FIG. 13) of the second engagement member 12 and at the same time, the other end portion of the second engagement member 12 is downwardly displaced on the basis of the engagement between the inclined slot 17 and the pin 18.
As a result, the engagement between the second engagement teeth 13 formed on the upper surface of the other end portion of the second engagement member 12 and the first engagement teeth 10 on the lower surface of the first engagement member 9 fixed to the lower surface of the rear steering column 4 is released. In this state, the rear steering column 4 becomes rockable about the lateral shafts 6, 6 (within a range in which a pin 19 projectedly provided on a side of the rear steering column 4 can be displaced inside an arcuate slot 20 formed in the support bracket 5). On the basis of this rocking movement, the height position of a steering wheel fixed to the end portion of the steering shaft 1 inserted in the rear steering column 4 becomes adjustable.
When the height position of the steering wheel is adjusted in this manner, the tilt lever 7 is rocked clockwisely as viewed in FIG. 13. With this rocking movement, the roller 15 moves into below the other end portion of the second engagement member 12 and pushes the other end portion of this second engagement member 12 upwardly. Thus, it brings the second engagement teeth 13 formed on the upper surface of this other end portion into engagement with the first engagement teeth 10 formed on the lower surface of the first engagement member 9 fixed to the lower surface of the rear steering column 4. As a result, the rear steering column 4 does not rotate about the lateral shafts 6, 6, and the steering wheel is kept in its adjusted height position. A resilient force, which tends to rock the tilt lever 7 clockwisely as viewed in FIG. 13, is imparted by a tension spring 21 to the tilt lever 7 and therefore it never happens that the roller 15 inadvertently retracts from below the second engagement member 12.
In the case of the conventional tilt type steering apparatus constructed and used as described above, the first engagement member 9 is fixed to the lower surface of the front end portion of the rear steering column 4 and further, the rear end portion of the second engagement member 12 and the roller 15 are brought into engagement under the first engagement member 9. Therefore, a relatively large space for providing these members 9, 12 and 15 therein is required below the front end portion of the rear steering column 4. When incorporated into an actual automobile, these members 9, 12 and 15 are covered with a cover called a column cover, but the position of the lower surface of this column cover becomes lower and a driver's knee becomes liable to interfere with this column cover, and this is not preferable.
Also, the first engagement member 9 is fixed to the lower surface of the front end portion of the rear steering column 4, but the lengthwise dimension of this first engagement member 9 becomes great. Also, when a combination switch for operating lights, wipers, etc. is to be provided, for example, on the outer peripheral surface of the rear steering column 4, it is necessary to provide it rearwardly of the first engagement member 9. Accordingly, the lengthwise dimension of the rear steering column 4 is liable to become greater than necessary.
When the lengthwise dimension of the rear steering column 4 becomes great, a force applied to the engaged portions of the first and second engagement members 9 and 12 by a moment force applied to the rear steering column 4 through the steering wheel becomes great. Accordingly, in order to prevent the two engagement members 9 and 12 from being brought out of engagement by the force applied to the steering wheel, it becomes necessary to make these two engagement members 9 and 12 large and strong. As a result, not only does the position of the lower end of the column cover become even lower, but also the weight thereof increases.